Lens module

ABSTRACT

A lens module includes lenses sequentially arranged from an object side toward an image plane sensor and having respective refractive powers. A second lens of the lenses has a convex object-side surface and a convex image-side surface. A first lens and a third lens of the lenses are symmetrical to each other in relation to the second lens.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/872,765 filed on May 12, 2020, which is a continuation of U.S. patentapplication Ser. No. 14/964,771 filed on Dec. 10, 2015, now U.S. Pat.No. 10,690,885 issued on Jun. 23, 2020, and claims the benefit under 35USC 119(a) of Korean Patent Application No. 10-2014-0177447 filed onDec. 10, 2014, in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND 1. Field

The following description relates to a lens module having an opticalsystem including five lenses.

2. Description of Related Art

A lens module mounted in a camera of a mobile communications terminalcommonly includes a plurality of lenses. For example, the lens moduleincludes five lenses as a high-resolution optical system.

However, when the high-resolution optical system is configured using aplurality of lenses as described above, a length (a distance from anobject-side surface of a first lens to an image sensor) of the opticalsystem increases. In this case, it is difficult to install the lensmodule in a slim mobile communications terminal. Therefore, a demandexists to develop a lens module having an optical system of decreasedlength.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In accordance with an embodiment, there is provided a lens module,including: lenses sequentially arranged from an object side toward animage plane sensor and including refractive power, respectively, whereina second lens of the lenses may have a convex object-side surface and aconvex image-side surface, and a first lens and a third lens of thelenses are symmetrical to each other in relation to the second lens.

The first lens may have a meniscus shape.

The first lens may have a convex object-side surface.

The first lens may have a concave image-side surface.

The fourth lens may have a concave object-side surface.

At least one of an object-side surface and an image-side surface of thefourth lens may be concave.

The fifth lens may have a convex object-side surface.

The fifth lens may have a concave image-side surface.

The lens module may further include a stop disposed between the secondlens and the third lens.

In accordance with an embodiment, there is provided a lens module,including: a first lens with a first refractive power; a second lenswith a second refractive power; a third lens with the second refractivepower; a fourth lens with the first refractive power; and a fifth lenswith the first refractive power and including an inflection point on animage-side surface, wherein the first to fifth lenses are sequentiallyarranged from an object side to an image side.

The first refractive power may be a negative refractive power.

The second refractive power may be a positive refractive power.

The lens module may satisfy 20<|V1−V2| in which V1 is an Abbe number ofthe first lens and V2 may be an Abbe number of the second lens.

The lens module may satisfy 20<V3-V4 in which V3 is an Abbe number ofthe third lens and V4 is an Abbe number of the fourth lens.

The lens module may satisfy 1.0<|(1/f1+1/f2)/(1/f3+1/f4+1/f5)|<4.0 inwhich f1 is a focal length of the first lens, f2 is a focal length ofthe second lens, f3 is a focal length of the third lens, f4 is a focallength of the fourth lens, and f5 is a focal length of the fifth lens.

The lens module may satisfy 1.0<|(r1+r2)/(r5+r6)|<3.0 in which r1 is aradius of curvature of an object-side surface of the first lens, r2 is aradius of curvature of an image-side surface of the first lens, r5 is aradius of curvature of an object-side surface of the third lens, and r6is a radius of curvature of an image-side surface of the third lens.

In accordance with an embodiment, there is provided a lens module,including: lenses sequentially arranged from an object side toward animage plane sensor and including refractive power, respectively, whereina refractive power of a first lens of the lenses is stronger than arefractive power of a fourth lens of the lenses, and the fourth lensincludes a shape substantially symmetrical to a shape of the first lens.

A second lens, a third lens, and a fifth lens of the lenses may have apositive refractive power.

A second lens of the lenses may have a strongest refractive power of thelenses and a fifth lens may have a weakest refractive power of thelenses.

An object-side surface of the first lens is convex and an image-sidesurface of the fourth lens may be substantially convex.

An image-side surface of the first lens is concave and an object-sidesurface of the fourth lens may be concave.

A third lens of the lenses may have the same refractive power as asecond lens of the lenses.

The first lens may have a meniscus shape convex toward an object and athird lens of the lenses may have a meniscus shape convex toward animage plane.

The first lens may have a meniscus shape convex toward an image planeand a third lens of the lenses may have a meniscus shape convex towardan object.

An object-side surface of a third lens of the lenses may besubstantially concave in a paraxial region and flattens at an edgeportion thereof.

The first lens and the fourth lens may be formed of a material includinga refractive index of at least 1.60.

The first lens and the fourth lens may include an Abbe number of 30 orless.

The first lens and a second lens of the lenses may have a refractivepower symmetrical with a third lens of the lenses and the fourth lens.

The first and second lenses may have a negative refractive power and apositive refractive power, respectively, and the third and fourth lensesmay have a positive refractive power and a negative refractive power,respectively.

The first lens and a second lens of the lenses may have symmetricalshapes with a third lens of the lenses and the fourth lens,respectively.

The first and second lenses may have a meniscus shape convex toward anobject, and the third and fourth lenses have a meniscus shape convextoward an image plane.

Abbe numbers of the first and second lenses may be symmetrical with Abbenumbers of the third and fourth lenses.

In accordance with an embodiment, there is provided a lens module,including: lenses sequentially arranged from an object side toward animage plane sensor and including refractive power, respectively, whereina first lens, a fourth lens, and a fifth lens of the lenses have a samerefractive power, and wherein the first lens may have a strongestrefractive power among the lenses and the fifth lens may have a weakestrefractive power among the lenses, and the fourth lens includes a shapesubstantially symmetrical and opposite to a shape of the first lens.

The first lens, the fourth lens, and the fifth lens may have a negativerefractive power.

The first lens may have a meniscus shape convex toward an object, andthe fourth lens may have a meniscus shape convex toward an image plane.

A second lens of the lenses may have a same refractive power as that ofa third lens lenses, and the second lens may have an opposite shape tothat of the third lens.

The second lens may have a meniscus shape convex toward an object, andthe third lens may have a meniscus shape convex toward an image plane.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view of a lens module, according to a first embodiment.

FIG. 2 is graphs having curves which represent aberrationcharacteristics of the lens module of FIG. 1 .

FIG. 3 is a table illustrating characteristics of lenses illustrated inFIG. 1 .

FIG. 4 is a table representing aspheric coefficients of the lens moduleillustrated in FIG. 1 .

FIG. 5 is a view of a lens module, according to a second embodiment.

FIG. 6 is graphs having curves which represent aberrationcharacteristics of the lens module of FIG. 5 .

FIG. 7 is a table illustrating the characteristics of the lensesillustrated in FIG. 5 .

FIG. 8 is a table representing aspheric coefficients of the lens moduleof FIG. 5 .

FIG. 9 is a view of a lens module, according to a third embodiment.

FIG. 10 is graphs having curves which represent aberrationcharacteristics of the lens module of FIG. 9 .

FIG. 11 is a table illustrating the characteristics of lensesillustrated in FIG. 9 .

FIG. 12 is a table representing aspheric coefficients of the lens moduleof FIG. 9 .

FIG. 13 is a view of a lens module, according to a fourth embodiment.

FIG. 14 is graphs having curves which represent aberrationcharacteristics of the lens module of FIG. 13 .

FIG. 15 is a table illustrating the characteristics of lensesillustrated in FIG. 13 .

FIG. 16 is a table representing aspheric coefficients of the lens moduleof FIG. 13 .

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals will be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/ormethods described herein will be apparent to one of ordinary skill inthe art. For example, the sequences of operations described herein aremerely examples, and are not limited to those set forth herein, but maybe changed as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various lenses, these lenses shouldnot be limited by these terms. These terms are only used to distinguishone lens from another lens. These terms do not necessarily imply aspecific order or arrangement of the lenses. Thus, a first lensdiscussed below could be termed a second lens without departing from theteachings of the various embodiments.

In one illustrative example, a first lens refers to a lens closest to anobject or a subject from which an image is captured. A fifth lens is alens closest to an image plane or an image sensor. In addition, a frontportion is a portion of a lens module close to the object or thesubject, and a rear portion is a portion of a lens module close to theimage plane or the image sensor. In addition, a first surface of eachlens refers to a surface of the lens closest to the object or thesubject, and a second surface of each lens refers to a surface of thelens closest to the image plane or the image sensor. All of radii ofcurvatures, thicknesses, optical axis distances from a first surface ofthe first lens to the image plane (OALs), distances on the optical axisbetween the stop and the image sensor (SLs), image heights (ImgHs or IMGHTs), and back focus lengths (BFLs) of the lenses, an overall focallength of an optical system, and a focal length of each lens are statedin millimeters (mm). Additionally, thicknesses of lenses, gaps betweenthe lenses, OALs, and SLs are distances measured based on an opticalaxis of the lenses.

Further, concerning lens shapes, a statement that a surface of a lens isconvex means that an optical axis portion of a corresponding surface isconvex. A statement that a surface of a lens is concave means that anoptical axis portion of a corresponding surface is concave. Therefore,although it may be stated that one surface of a lens is convex, an edgeportion of the lens may be concave. Likewise, although it may be statedthat one surface of a lens is concave, an edge portion of the lens maybe convex. In other words, a paraxial region of a lens may be convex,while the remaining portion of the lens outside the paraxial region maybe convex, concave, or flat. Further, a paraxial region of a lens may beconcave, while the remaining portion of the lens outside the paraxialregion may be convex, concave, or flat.

A lens module includes an optical system including a plurality oflenses. In one embodiment, the optical system of the lens moduleincludes five lenses having refractive power. However, the lens moduleis not limited to only including five lenses. The lens module mayinclude from four lenses up to six lenses without departing from thescope of the embodiments herein described. In accordance with anillustrative example, the embodiments described of the optical systeminclude five lenses with a particular refractive power. However, aperson of ordinary skill in the relevant art will appreciate that thenumber of lenses in the optical system may vary, for example, betweentwo to six lenses, while achieving the various results and benefitsdescribed hereinbelow. Also, although each lens is described with aparticular refractive power, a different refractive power for at leastone of the lenses may be used to achieve the intended result.

Furthermore, the lens module includes other structural components thatdo not have refractive power, such as, the lens module includes a stopcontrolling an amount of light. As another example, the lens module mayfurther include an infrared cut-off filter blocking infrared light. Asanother example, the lens module may further include an image sensor,for instance, an imaging device, to convert an image of a subjectincident thereon through the optical system into electrical signals. Asanother example, the lens module may further include a gap maintainingmember to adjust a gap between lenses. In one illustrative embodiment,the gap maintaining member adjusts each lens to be at a distance fromeach other and the filter. However, in an alternative embodiment, thegap maintaining member may adjust each lens so that at least two of thelenses are in contact with each other, while the other lenses and thefilter have a predetermined gap there between. In a further embodiment,the gap maintaining member may adjust each lens so that at least two ofthe lenses are in contact with each other, while the other lenses have agap there between and at least one of the lenses is in contact with thefilter.

First to fifth lenses are formed using a material having a refractiveindex different from that of air. For example, the first to fifth lensesare formed of plastic or glass. In an example, at least one of the firstto fifth lenses has an aspherical surface shape. In another example,only the fifth lens of the first to fifth lenses has the asphericalsurface shape. Further, at least one surface of each of the first tofifth lenses may be aspherical. For instance, the aspherical surface ofeach lens is represented by the following Equation 1.

$\begin{matrix}{Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {Fr}^{14} + {Gr}^{16} + {Hr}^{18} + {Jr}^{20}}} & (1)\end{matrix}$

In an example, c is an inverse of a radius of curvature of acorresponding lens, K is a conic constant, and r refers to a distancefrom a certain point on an aspheric surface to an optical axis in adirection perpendicular to the optical axis. In addition, constants A,B, C, D, E, F, G, H, and J are respectively 4th, 6th, 8th, 10th, 12th,14th, 16th, 18th, and 20th order aspheric coefficients. In addition, Zis a distance between the certain point on the aspheric surface at thedistance r and a tangential plane meeting the apex of the asphericsurface of the lens.

The optical system configuring the lens module has a field of view (FOV)of 60 degrees or more. Therefore, the lens module, according to anembodiment, may easily capture an image is observable at a wide field ofview.

The lens module includes first to fifth lenses having refractive power.The lens module also includes a filter, a stop, and an image sensor.Hereinafter, structural components included in the lens module will bedescribed.

Each of the first through fifth lenses has a refractive power, eithernegative or positive. For instance, in one configuration, the first lenshas a first refractive power. For example, the first lens has a negativerefractive power.

The first lens has a meniscus shape. For example, a first surface or anobject-side surface of the first lens is convex, and a second surface oran image-side surface of the first lens is concave.

The first lens has an aspheric surface. For example, two surfaces of thefirst lens are aspheric. The first lens is formed of a material havingrelatively high light transmissivity and excellent workability. Forexample, the first lens is formed of plastic or other organic polymers.However, a material of the first lens is not limited to plastic. Forexample, the first lens may be formed of glass.

The first lens is formed of a material having a relatively highrefractive index. For example, the first lens is formed of a materialhaving a refractive index of 1.60 or more. In one example, the firstlens has an Abbe number of 30 or less. The first lens formed of thismaterial easily refracts light while having a relatively smallcurvature. Therefore, the first lens formed of this material is easilymanufactured and is advantageous in terms of lowering a defect ratedepending on manufacturing tolerance. In addition, the first lens formedof this material enables a distance between lenses to be decreased,providing an advantage for miniaturizing the lens module.

The second lens has a second refractive power. For example, the secondlens has a refractive power opposite that of the first lens. Forexample, the second lens has a positive refractive power.

The second lens has at least one convex surface. For example, the firstsurface of the second lens is convex. As another example, the secondsurface of the second lens is convex. As another example, the first andsecond surfaces of the second lens are both convex.

The second lens has an aspheric surface. For example, two opposingsurfaces of the second lens are aspheric. The second lens is formed of amaterial having relatively high light transmissivity and excellentworkability. For example, the second lens is formed of plastic or otherorganic polymers. However, the material of the second lens is notlimited to plastic. For example, the second lens may be formed of glass.

A third lens has a second refractive power. For example, the third lenshas the same refractive power as the second lens. For example, when thesecond lens has positive refractive power, the third lens has a positiverefractive power. As another example, when the second lens has negativerefractive power, the third lens has a negative refractive power.However, the configuration of the third lens is not limited to have thesame refractive power as the second lens. For instance, in analternative configuration, the third lens has a refractive powerindependent of the refractive power of the second lens. The third lensmay have a refractive power to be the same as the refractive power as afourth lens, to be later described, or the first lens.

The third lens has a shape symmetrical with that of the first lens. Forexample, when the first lens has a meniscus shape convex toward anobject, the third lens has a meniscus shape convex toward an imageplane. As another example, when the first lens has a meniscus shapeconvex toward an image plane, the third lens has a meniscus shape convextoward an object. In one example, an object-side surface of the thirdlens is concave substantially in a paraxial region and flattens at anedge portion thereof. In this example, an image-side surface of thethird lens is convex in a paraxial region.

The third lens has an aspheric surface. For example, two opposingsurfaces of the third lens are aspheric. The third lens is formed of amaterial having relatively high light transmissivity and excellentworkability. For example, the third lens is formed of plastic or otherorganic polymers. However, the material of the third lens is not limitedto plastic. For example, the third lens may be formed of glass.

A fourth lens has a first refractive power. For example, the fourth lenshas the same refractive power as the first lens. For example, when thefirst lens has a positive refractive power, the fourth lens has apositive refractive power. As another example, when the first lens has anegative refractive power, the fourth lens has a negative refractivepower. However, the configuration of the fourth lens is not limited tohave the same refractive power as the first lens. For instance, in analternative configuration, the fourth lens has a refractive powerindependent of the refractive power of the first lens. The fourth lensmay have a refractive power to be the same as the refractive power as afifth lens, to be later described, or the third lens.

The fourth lens has a shape substantially symmetrical to that of thefirst lens. For example, when an object-side surface of the first lensis convex, the image-side surface of the fourth lens is substantiallyconvex. As another example, when the image-side surface of the firstlens is concave, the object-side surface of the fourth lens is concave.In one example, an object-side surface of the fourth lens is concavesubstantially in a paraxial region and flattens at an edge portionthereof. In this example, an image-side surface of the fourth lens isconvex in a paraxial region.

The fourth lens has an aspheric surface. For example, two opposingsurfaces of the fourth lens are aspheric. The fourth lens is formed of amaterial having relatively high light transmissivity and excellentworkability. For example, the fourth lens may be formed of plastic orother organic polymer. However, the material of the fourth lens is notlimited to plastic. For example, the fourth lens may be formed of glass.

The fourth lens is formed of the same material as or a material similarto that of the first lens. For example, the fourth lens is formed of amaterial having a refractive index of 1.60 or more like the first lens.In one example, the fourth lens has an Abbe number of 30 or less. Thefourth lens formed of this material easily refracts light, even whilehaving a relatively small curvature. Therefore, the fourth lens formedof this material is easily manufactured and is advantageous in terms oflowering a defect rate depending on manufacturing tolerance. Inaddition, the fourth lens formed of this material decreases a distancebetween lenses, thus, allowing a miniaturization of the lens module.

A fifth lens has a first refractive power. For example, the fifth lenshas substantially the same refractive power as the first lens. Forexample, when the first lens has positive refractive power, the fifthlens has a positive refractive power. As another example, when the firstlens has negative refractive power, the fifth lens has a negativerefractive power. However, the configuration of the fifth lens is notlimited to have the same refractive power as the first lens. Forinstance, in an alternative configuration, the fifth lens has arefractive power independent of the refractive power of the first lens.The fifth lens may have a refractive power to be the same as therefractive power as the second, the third, or the fourth lenses.

The fifth lens is convex toward an object. For example, the firstsurface of the fifth lens is convex and the second surface thereof isconcave.

The fifth lens is shaped to include an inflection point. For example,one or more inflection points are formed on an object-side surface ofthe fifth lens. As another example, one or more inflection points areformed on an image-side surface of the fifth lens. The object-sidesurface of the fifth lens, configured as described above, has a shape inwhich a convex portion and a concave portion are alternately formed.Similarly, the image-side surface of the fifth lens is concave in aparaxial portion, for example, at the center of the lens, while an edgeportion thereof is convex. In an embodiment, the image-side surface ofthe fifth lens is concave in a paraxial region and gradually curves tobe convex towards edge portions thereof. In an embodiment, theobject-side surface of the fifth lens is convex is the paraxial regionand gradually curves to be concave outside the paraxial region andflattens at edge portions thereof.

The fifth lens has an aspheric surface. For example, two opposingsurfaces of the fifth lens are aspheric. The fifth lens is formed of amaterial having relatively high light transmissivity and excellentworkability. For example, the fifth lens may be formed of plastic orother organic polymer. However, the material of the fifth lens is notlimited to plastic. For example, the fifth lens may be formed of glass.

The filter is disposed between the fifth lens and an image sensor. Thefilter blocks a specific wavelength of incident light. For example, thefilter is an infrared cut-off filter for blocking infrared rays. Thefilter is formed of plastic or glass. For example, the filter has anAbbe number of 60 or more.

In one configuration, the stop is disposed between the second lens andthe third lens. For example, the stop may be disposed between animage-side surface of the second lens and an object-side surface of thethird lens. In alternative configurations, the stop may be disposedbetween any other of the first through five lenses illustrated in FIG. 1.

The image sensor is configured to realize high resolution of 1300megapixels. For example, a unit size of the pixels configuring the imagesensor may be 1.12 μm or less.

The lens module has a relatively wide field of view. For example, theoptical system of the lens module has a field of view of about 60degrees or more. In addition, the lens module has a relatively shorttotal track length (TTL). For example, the TTL, which is an overalllength or a distance from the object-side surface of the first lens tothe image sensor of the optical system configuring the lens module, is4.80 mm or less. Therefore, the lens module, according to an embodiment,enables miniaturization thereof.

The lens module is configured in such a way that the first to fourthlenses are approximately symmetrical to each other in relation to thestop. For example, the first and second lenses have a refractive powersymmetrical with the third and fourth lenses. For example, when thefirst and second lenses have negative and positive refractive power,respectively, the third and fourth lenses have positive and negativerefractive power, respectively. As another example, the first and secondlenses have symmetrical shapes with the third and fourth lenses,respectively. For example, when the first and second lenses have ameniscus shape convex toward an object, the third and fourth lenses havea meniscus shape convex toward an image plane. This configuration of thefirst to fourth lenses is advantageous in terms of compensating for adistortion aberration and an astigmatic aberration. As another example,Abbe numbers of the first and second lenses are distributed to besymmetrical with Abbe numbers of the third and fourth lenses. Forexample, the first lens have approximately the same Abbe number as thefourth lens, and the second lens have approximately the same Abbe numberas third lens. The distribution characteristics of Abbe numbers of thefirst to fourth lenses are advantageous in terms of compensating forcolor aberration.

The lens module satisfies the following conditional formula 1.20<|V1−V2|  (Conditional Formula 1)

In the above conditional formula 1, V1 is an Abbe number of the firstlens, and V2 is an Abbe number of the second lens.

The above conditional formula 1 is a condition to compensate for coloraberration by the first and second lenses. For example, a combination ofthe first and second lenses which satisfy the above conditional formula1 effectively compensates for color aberration.

In addition, the lens module satisfies the following conditional formula2.20<V3−V4  (Conditional Formula 2)

In the above conditional formula 2, V3 is an Abbe number of the thirdlens, and V4 is an Abbe number of the fourth lens.

The above conditional formula 2 is a condition to compensate for coloraberration by the third and fourth lenses. For example, a combination ofthe third and fourth lenses that satisfy the above conditional formula 2effectively compensates for color aberration.

In addition, the lens module satisfies the following conditional formula3.1.0<|(1/f1+1/f2)/(1/f3+1/f4+1/f5)|<4.0  (Conditional Formula 3)

In the above conditional formula 3, f1 is a focal length of the firstlens, f2 is a focal length of the second lens, f3 is a focal length ofthe third lens, f4 is a focal length of the fourth lens, and f5 is afocal length of the fifth lens.

The above conditional formula 3 is a condition to obtain improveddistribution of refractive power of the first to fifth lenses. Forexample, an optical system that satisfies the above conditional formula3 may be easily manufactured.

In addition, the lens module may satisfy the following conditionalformula 4.1.0<|(r1+r2)/(r5+r6)|<3.0  (Conditional Formula 4)

In the above conditional formula 4, r1 is a radius of curvature of anobject-side surface of the first lens, r2 is a radius of curvature of animage-side surface of the first lens, r5 is a radius of curvature anobject-side surface of the third lens, and r6 is a radius of curvatureof an image-side surface of the third lens.

The above conditional formula 4 is a condition to improve shapes of thefirst and third lenses.

In addition, the lens module satisfies the following conditional formula5.0.7<d3/d4<1.2  (Conditional Formula 5)

In the above conditional formula 5, d3 is a thickness of the second lensand d4 is a distance from an image-side surface of the second lens to anobject-side surface of the third lens.

A lens module, according to a first embodiment, will be described withreference to FIG. 1 .

A lens module 100 includes an optical system including a first lens 110,a second lens 120, a third lens 130, a fourth lens 140, and a fifth lens150. In addition, the lens module 100 includes an infrared cut-offfilter 70 and an image sensor 80. In addition, the lens module 100 alsoincludes a stop (ST). For example, the stop is disposed between thesecond lens and the third lens.

In an embodiment, the first lens 110 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 120 has a positive refractive power,and two opposing surfaces thereof are convex. The third lens 130 has apositive refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is convex. The fourth lens 140 has anegative refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is convex. The fifth lens 150 has anegative refractive power, and an object-side surface thereof is convexand an image-side surface thereof is concave. In addition, one or moreinflection points are formed on each of the object-side surface and theimage-side surface of the fifth lens.

In an embodiment, all of the first lens 110, the fourth lens 140, andthe fifth lens 150 have a negative refractive power, as described above.Among these lenses, the fifth lens 150 has the weakest refractive power,and the first lens 110 has the strongest refractive power. However, aperson of skill in the art will appreciate that in alternativeembodiments, at least one of the first lens 110, the fourth lens 140,and the fifth lens 150 has a negative refractive power. Also, therefractive power of the first lens 110 may be weaker than the refractivepower of the fourth lens 140. Further, the refractive power of the firstlens 110 may be weaker than the refractive power of the fifth lens 150.

FIG. 2 is graphs having curves which represent aberrationcharacteristics of the lens module.

FIG. 3 is a table illustrating the characteristics of lenses configuringthe lens module. In FIG. 3 , Surface Nos. 1 and 2 indicate the firstsurface or the object-side surface and the second surface or theimage-side surface of the first lens, and Surface Nos. 3 and 4 indicatethe first and second surfaces of the second lens. Similarly, SurfaceNos. 5 to 10 indicate first and second surfaces of the third to fifthlenses, respectively. In addition, Surface Nos. 11 and 12 indicate firstand second surfaces of the infrared cut-off filter.

FIG. 4 is a table representing conic constants and aspheric coefficientsof the lenses configuring the lens module. In FIG. 4 , the first columnof the table indicates Surface Nos. 1 through 10 of respective surfacesof the first to fifth lenses, and K and A to F in the top row of thetable indicate conic constants (K) and aspheric coefficients (A to F) ofrespective surfaces of the lenses.

A lens module, according to a second embodiment, will be described withreference to FIG. 5 .

A lens module 200 has an optical system including a first lens 210, asecond lens 220, a third lens 230, a fourth lens 240, and a fifth lens250. In addition, the lens module 200 includes an infrared cut-offfilter 70 and an image sensor 80. In addition, the lens module 200 alsoincludes a stop (ST). For example, the stop is disposed between thesecond lens and the third lens.

In the embodiment, the first lens 210 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 220 has a positive refractive power,and two opposing surfaces thereof are convex. The third lens 230 has apositive refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is convex. The fourth lens 240 has anegative refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is concave. The fifth lens 250 has anegative refractive power, and an object-side surface thereof is convexand an image-side surface thereof is concave. In addition, one or moreinflection points are formed on each of the object-side surface and theimage-side surface of the fifth lens.

In the embodiment, all of the first lens 210, the fourth lens 240, andthe fifth lens 250 have a negative refractive power. Among these, thefifth lens 250 has the weakest refractive power, and the first lens 210has the strongest refractive power. However, a person of skill in theart will appreciate that in alternative embodiments, at least one of thefirst lens 210, the fourth lens 240, and the fifth lens 150 has anegative refractive power. Also, the refractive power of the first lens210 may be weaker than the refractive power of the fourth lens 240.Further, the refractive power of the first lens 210 may be weaker thanthe refractive power of the fifth lens 250.

FIG. 6 is graphs having curves that represent aberration characteristicsof the lens module.

FIG. 7 is a table illustrating the characteristics of lenses configuringthe lens module. In FIG. 7 , Surface Nos. 1 and 2 indicate the firstsurface or the object-side surface and the second surface or theimage-side surface of the first lens, and Surface Nos. 3 and 4 indicatethe first and second surfaces of the second lens. Similarly, SurfaceNos. 5 to 10 indicate first and second surfaces of the third to fifthlenses, respectively. In addition, Surface Nos. 11 and 12 indicate firstand second surfaces of the infrared cut-off filter.

FIG. 8 is a table representing conic constants and aspheric coefficientsof the lenses configuring the lens module. In FIG. 8 , the first columnof the table indicates Surface Nos. 1 through 10 of respective surfacesof the first to fifth lenses, and K and A to F in the top row of thetable indicate conic constants (K) and aspheric coefficients (A to F) ofrespective surfaces of the lenses.

A lens module according to a third embodiment will be described withreference to FIG. 9 .

A lens module 300 has an optical system including a first lens 310, asecond lens 320, a third lens 330, a fourth lens 340, and a fifth lens350. In addition, the lens module 300 may include an infrared cut-offfilter 70 and an image sensor 80. In addition, the lens module 300further includes a stop (ST). For example, the stop is disposed betweenthe second lens and the third lens.

In the embodiment, the first lens 310 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 320 has a positive refractive power,and two opposing surfaces thereof is convex. The third lens 330 has apositive refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is convex. The fourth lens 340 has anegative refractive power, and an object-side surface thereof is concaveand an image-side surface thereof is convex. The fifth lens 350 has apositive refractive power, and an object-side surface thereof is convexand an image-side surface thereof is concave. In addition, one or moreinflection points are formed on each of the object-side surface and theimage-side surface of the fifth lens.

In an embodiment, both of the first lens 310 and the fourth lens 340have a negative refractive power. In one example, the first lens 310 hasa weaker refractive power than that of the fourth lens 340. All of thesecond lens 320, the third lens 330, and the fifth lens 350 have apositive refractive power. In an example, the second lens 320 has thestrongest refractive power and the fifth lens 350 has the weakestrefractive power. However, a person of skill in the art will appreciatethat in alternative embodiments, at least one of the second lens 320,the fourth lens 340, and the fifth lens 350 has a positive refractivepower. Also, the refractive power of the second lens 320 may be weakerthan the refractive power of the fifth lens 350.

FIG. 10 is graphs having curves which represent aberrationcharacteristics of the lens module.

FIG. 11 is a table illustrating the characteristics of the lensesconfiguring the lens module. In FIG. 11 , Surface Nos. 1 and 2 indicatethe first surface or the object-side surface and the second surface orthe image-side surface of the first lens, and Surface Nos. 3 and 4indicate the first and second surfaces of the second lens. Similarly,Surface Nos. 5 to 10 indicate first and second surfaces of the third tofifth lenses, respectively. In addition, Surface Nos. 11 and 12 indicatefirst and second surfaces of the infrared cut-off filter.

FIG. 12 is a table representing conic constants and asphericcoefficients of lenses configuring the lens module. In FIG. 12 , thefirst column of the table indicate Surface Nos. 1 through 10 ofrespective surfaces of the first to fifth lenses, and K and A to F inthe top row of the table indicate conic constants (K) and asphericcoefficients (A to F) of respective surfaces of the lenses.

A lens module, according to a fourth embodiment, will be described withreference to FIG. 13 .

A lens module 400 has an optical system including a first lens 410, asecond lens 420, a third lens 430, a fourth lens 440, and a fifth lens450. In addition, the lens module 400 includes an infrared cut-offfilter 70 and an image sensor 80. In addition, the lens module 400further includes a stop (ST). For example, the stop is disposed betweenthe second lens and the third lens.

In the embodiment, the first lens 410 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The second lens 420 has a positive refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The third lens 430 has a positive refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The fourth lens 440 has a negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The fifth lens 450 has a negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, one or more inflection points areformed on each of the object-side surface and the image-side surface ofthe fifth lens.

In the embodiment, all of the first lens 410, the fourth lens 440, andthe fifth lens 450 have a negative refractive power. Among these, thefifth lens 450 has the weakest refractive power, and the first lens 410has the strongest refractive power. However, a person of skill in theart will appreciate that in alternative embodiments, at least one of thefirst lens 410, the fourth lens 440, and the fifth lens 450 has anegative refractive power. Also, the refractive power of the first lens410 may be weaker than the refractive power of the fifth lens 450.

The lens module 400 is formed in such a way that the first lens 410 tothe fourth lens 440 are symmetrical to each other in relation to thestop. For example, the first lens 410 has the same refractive power asthat of the fourth lens 440, but has an opposite shape to that of thefourth lens 440. For example, the first lens 410 has a meniscus shapeconvex toward an object, while the fourth lens 440 has a meniscus shapeconvex toward an image plane. As another example, the second lens 420has the same refractive power as that of the third lens 430, but has anopposite shape to that of the third lens 430. For example, the secondlens 420 has a meniscus shape convex toward an object, while the thirdlens 430 has a meniscus shape convex toward an image plane.

FIG. 14 is graphs having curves which represent aberrationcharacteristics of the lens module.

FIG. 15 is a table illustrating the characteristics of the lensesconfiguring the lens module. In FIG. 15 , Surface Nos. 1 and 2 indicatethe first surface or the object-side surface and the second surface orthe image-side surface of the first lens, and Surface Nos. 3 and 4indicate the first and second surfaces of the second lens. Similarly,Surface Nos. 5 to 10 indicate first and second surfaces of the third tofifth lenses, respectively. In addition, Surface Nos. 11 and 12 indicatefirst and second surfaces of the infrared cut-off filter.

FIG. 16 is a table representing conic constants and asphericcoefficients of the lenses configuring the lens module. In FIG. 16 , thefirst column of the table indicates Surface Nos. 1 through 10 ofrespective surfaces of the first to fifth lenses, and K and A to F inthe top row of the table indicate conic constants (K) and asphericcoefficients (A to F) of respective surfaces of the lenses.

Table 1 below illustrates optical characteristics of a lens module,according to the first to fourth embodiments. The lens module has anoverall focal length f of approximately 2.80 to 3.70. A focal length f1of the first lens of the lens module is determined to be in the range ofapproximately −6.0 to −5.0. A focal length f2 of the second lens of thelens module is determined to be in the range of approximately 1.60 to2.10. A focal length f3 of the third lens of the lens module isdetermined to be in the range of approximately 5.0 to 17.0. A focallength f4 of the fourth lens of the lens module is determined to be inthe range of approximately −7.0 to −4.0. A focal length f5 of the fifthlens of the lens module is determined to be approximately −15.0 orgreater. An overall length TTL of an optical system of the lens moduleis determined to be in the range of approximately 4.20 to 4.80. A fieldof view FOV of the lens module is determined to be in the range ofapproximately 60.0 to 80.0.

TABLE 1 First Second Third Fourth Remark embodiment embodimentembodiment embodiment f 2.914 3.600 3.491 3.402 f1 −5.405 −5.829 −5.898−5.538 f2 1.757 1.914 1.944 1.855 f3 5.943 15.867 12.495 7.641 f4 −6.530−6.589 −4.711 −5.543 f5 −8.731 −9.221 144.824 −13.822 TTL 4.316 4.7264.622 4.427 FOV 74.85 63.55 65.14 66.49 ImgH 2.230 2.230 2.230 2.230

Table 2 below shows values of the conditional formulas 1 to 5 of thelens modules, according to the first to fourth embodiments.

TABLE 2 Conditional First Second Third Fourth Formula embodimentembodiment embodiment Embodiment |V1-V2| 30.70 30.70 30.70 30.70 V3-V430.70 30.70 30.70 30.70 |(1/f1 + 1/f2)/ 3.864 1.780 2.751 2.941 (1/f 3+1/ f4 + 1/f5)| |(r1 + r2)/ 2.479 1.381 1.943 1.242 (r5 + r6)| d3/d40.857 1.021 0.769 1.087

As seen from Table 2 above, the lens modules, according to the first tofourth embodiments, satisfy all of the conditional formulas 1 to 5.

As set forth above, according to embodiments, a high-resolution opticalsystem may be realized.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A lens module comprising: a first lens havingnegative refractive power; a second lens having a refractive power; athird lens having a refractive power; a fourth lens having a concaveobject-side surface; and a fifth lens having negative refractive powerand a convex object-side surface, wherein the first to fifth lenses aresequentially arranged in ascending numerical order from an object sideof the lens module toward an image side of the lens module, and whereina radius of curvature of an image-side surface of the first lens isgreater than a radius of curvature of an image-side surface of the thirdlens.
 2. The lens module of claim 1, wherein the first lens has aconcave image-side surface.
 3. The lens module of claim 1, wherein thesecond lens has a convex object-side surface.
 4. The lens module ofclaim 1, wherein the second lens has a convex image-side surface.
 5. Thelens module of claim 1, wherein the fourth lens has a convex image-sidesurface.
 6. The lens module of claim 1, wherein the fifth lens has aconcave image-side surface.
 7. The lens module of claim 1, wherein thefifth lens has an inflection point formed on an image-side surface ofthe fifth lens.
 8. The lens module of claim 1, wherein1.0<|(r1+r2)/(r5+r6)|<3.0, where r1 is a radius of curvature of anobject-side surface of the first lens, r2 is a radius of curvature ofthe image-side surface of the first lens, r5 is a radius of curvature ofan object-side surface of the third lens, and r6 is a radius ofcurvature of the image-side surface of the third lens.
 9. The lensmodule of claim 1, wherein an overall length TTL of the lens module iswithin a range from 4.20 mm to 4.80 mm.
 10. The lens module of claim 1,wherein a focal length of the second lens is within a range from 1.60 mmto 2.10 mm.
 11. The lens module of claim 1, wherein a focal length ofthe fifth lens is −15.0 mm or greater.
 12. The lens module of claim 1,wherein a distance from an image-side surface of the second lens to anobject-side surface of the third lens is greater than a distance from animage-side surface of the fourth lens to the object-side surface of thefifth lens.